Long term stability of rh-Cu/Zn-superoxide dismutase (SOD)-liposomes prepared by the cross-flow injection technique following International Conference on Harmonisation (ICH)-guidelines

Abstract

The current market position of liposomes as drug carriers is still being discussed with regard to large scale production, product characterisation and the stability of the dispersions. In this study, long term stability of liposomal suspensions with encapsulated rh-Cu/Zn-superoxide dismutase was tested according to the International Conference on Harmonisation (ICH) recommendations. The guidelines of the ICH provide general requirements for stability testing for registration and export in particular. The Institute of Applied Microbiology has examined a process to produce large amounts of pharmaceutical-grade liposomes for the treatment of inflammatory diseases by topical application. For the evaluation of its long-term storage stability, liposomal stability and protein stability were tested under appropriate conditions. Therefore, size alterations of the vesicles, protein release and protein activity were evaluated. During the observation period, neither significant alterations of the liposomes nor any protein degradation could be detected. In the light of these findings our liposomal formulations seem to provide chemical, physical and biological stability according to the definitions of the ICH. Appropriate lipid compounds and environmental factors, in combination with an optimised process and adequate storage conditions, facilitate the production of liposome dispersions suitable as drug carriers on the market.